Automotive front headlights are typically required to operate in both a low-beam and a high-beam mode. A low-beam mode is designed to restrict or constrain the upward projection of light, to avoid causing glare to oncoming road users. Most low-beam headlights are also tailored specifically for use on one side of the road only (either left or right), and are adapted to direct the major portion of their light toward the driver's own side of the road, while ‘dipping down’ on the other side—again to avoid causing glare to the oncoming vehicles. Headlight units typically achieve this by generating a substantially horizontal upper ‘cut-off’ in the projected light, above which is dark, below which is light. The cut-off profile dips downward on the driver's near-side direction (avoiding glare) but sweeps or steps upward on the driver's offside direction, to assist in illuminating road-signs and passing pedestrians.
Typically, the generation of such a low-beam requires the separate generation of two distinct component beams: a first to create the sharp stepped cut-off shape across the top of the beam profile, and a second to create the remaining spread of illumination below the cut-off line. This usually requires separate units to generate each component, which adds significant bulk, weight and cost to the headlight unit.
In addition to this, there exist parallel inadequacies in the generation of high beams within the headlight units. Dual high and low beam functionality is typically achieved by means either of a moveable (for example up/down) shield which allows switching between a lower cut off and a high cut off, or by means of a very thin shield. In the former case, it is necessary to provide actuation components (for example a solenoid) to facilitate the movement of the shield, which adds cost and complication to the device. In the latter case, the thin shields require highly precise manufacturing, necessitating computerised numerical control (CNC) methods for their production—again adding significant cost to the production process.
Desired therefore, to allow solution of one or both of these parallel problems, is a headlight unit providing generation of two distinct (but possibly overlapping) beam components, by means of a single, integrated module which does not necessarily require moving parts, wherein one or both of the beam components generate at least a low-beam having a stepped upper cut-off for preventing glare.